[Elecraft] [KX3] LiPol battery pack and KX3 - voltage vs output

[Thomas Horsten]

On 12 January 2012 17:02, Wayne Burdick <n6kr at elecraft.com> wrote:


> The KX3 can put out up to 12 W. At this power level we recommend using a
> 13-14 V power supply.
>
> On some bands the KX3 will put out 10 W with a supply voltage as low as 11
> V. This is ideal for use with gel-cells and car or motorcycle batteries.
>
> Below 11 V, the max power setting is 5.0 W, where the KX3 automatically
> switches the PA to a mode that's more efficient at low voltage/low power.
> On most bands, 5 W is possible with a 9.6-V supply, e.g. 8 internal NiMH
> cells.
>

Thanks for that info Wayne, basically the TX performance will be on par
with or better than the FT-817 with the Li-Pol cell (much better when it's
fully charged).

That said, does anyone on the list know of a circuit that could step up the
voltage of the 12V LiPol cell to a regulated clean 13.8V supply? It would
be great to be able to put out the full power continuously. I guess an
inverter and switched mode supply could be used but that would be far
overkill, does anyone know of any chips e.g. available from Farnell that
could be used in such a box? The LiPol should easily be able to deliver the
amps needed even when partially discharged, and the supply would have other
uses too.

73, Thomas